The present invention relates to a laser processing method and particularly, to a laser processing method preferable for a case where a head for an inkjet printer is produced.
1. (Prior Art)
An inkjet printer by which an ink drop is jetted onto a medium and a character or image can be formed, is well known. Such an ink drop is jetted from a head at the predetermined timing by using the piezoelectric effect. Hereupon, when the image is formed by using the inkjet printer, a complex color expression or edge expression is conducted by a combination of the ink drop jetted on the medium.
2. [Problems to be Solved by the Invention]
In this connection, in order to form a high quality image, it is necessary that a jetting exit of the ink drop formed on the head is arranged at small and minute intervals. However, because, to such a small structure, wiring cables or flow path regulating plate (a plate to regulate so that the ink does not enter into an unwanted position) are attached, it is necessary that the processing of the head is carefully conducted. Herein, in the conventional art, it is conducted that, in order to flow the current for diving the head, after the conductive film (for example, metallic layer) is attached on the surface of the head, the laser light is irradiated onto the surface, and an unwanted metallic layer is removed, and the surface is formed as an electrode. When such a laser light is used, the metallic layer is removed in a narrow width, and a minute head processing can be precisely conducted.
Conventionally, for the processing of metal or ceramics, the laser light irradiated from the CO2 laser as the gas laser, or the laser light of the basic wavelength (1064 nm) irradiated from the ND:YAG laser as a solid laser, is used. However, on the surface of the inkjet head which is an object to be processed, it is preferable that the surface is very smooth so that the wiring cables and parts of the flow path regulating plate can be adequately adhered so that the movement as the inkjet head is possible, and accordingly, it is necessary that, even after the processing, the smoothness is maintained. However, the processing using the laser light is naturally the thermal processing, and when the laser light is irradiated, on the surface after the processing, the soil or burr, dross are generated, and there is a problem in which the smoothness is hindered thereby. Further, there is also a probability that the de-poling (the polarity becomes a non-orientation situation)is generated in the piezoelectric material which is a material to be processed, by the heat accumulation effect when the laser light is irradiated.
In view of such a problem of the related art, the present invention is attained and an object of the present invention is to provide a laser processing method by which, while the processing surface condition of the material to be processed is maintained good, the precision processing can be conducted.